SDLPP: add option to specify render object alignment

sdlpp/sdlpp_vector.hpp

@@ -38,6 +38,9 @@ public:
         *this = *this - other;
         return *this;
     }
+    bool operator==( const Vec2D &other ) {
+        return other._x == _x && other._y == _y;
+    }
 
 private:
     T _x = 0.0;